1. Field of the Invention
The invention relates to a surface treating method, particularly to a method for treating the group III nitride semiconductor.
2. Description of the Prior Art
In the conventional semiconductor manufacturing process technology, the heterogeneous epitaxy method is often adopted to form the nitride semiconductor thin film or the nitride semiconductor thick film. It means to form the nitride semiconductor thin film (or thick film) on the non-nitride semiconductor substrate, such as the sapphire substrate. However, due to the difference of lattice constant exists between the non-nitride semiconductor substrate and the nitride semiconductor, thus 15% of lattice mismatch will be generated, and the defects of threading dislocations will be produced. These defects will influence the photoelectric characteristics of the light emitting diode (LED). Not only the power will be wasted, but also the surplus heat will be produced. If the conventional technology is employed to form the patterns on the nitride semiconductor, the method will be quite complicated actually.
As for the method to reduce the above-mentioned defects of threading dislocations at present, the Void-Assisted Separation (VAS), the Facet-Controlled Epitaxial Lateral Overgrowth (FACELO), and the Epitaxial lateral overgrowth (ELOG) are used to reduce the number of threading dislocations, and in order to reduce the defect density. However, the above-mentioned technologies need additional the semiconductor manufacturing processes, such as the photolithography process, and the dry etching process etc. These additional semiconductor manufacturing processes will increase the manufacturing cost.
In one of the prior art, such as Taiwan Patent No. 1271788, the GaN single chip substrate, the nitride semiconductor substrate, the nitride semiconductor device and the manufacturing method had been proposed. This patent discusses the GaN after grinding mainly. The scratches on surface can be annealed by ammonia+hydrogen (NH3+H2) to obtain smooth surface. The ammonia (NH3) also can provide hydrogen atom (H), but the total amount is insufficient, thus it is necessary to add hydrogen (H2) for the supplementation. The ammonia is the main gas, and the hydrogen gas is the auxiliary gas. The effect is to smoothen the surface, which is a result of the surface atom migration.
In another prior art, such as U.S. Pat. No. 5,814,239 about Gas-Phase Etching and Regrowth Method for Group 111—Nitride Crystals, the gas is used to etch group III nitride semiconductor surface mainly. The gas may be halogen gas (Such as F2, Cl2, Br2 and I2) or hydrogen halide gas (Such as HF, HCl, HBr and HI). The pressure is at 1 atm, and the temperature is 500° C.˜900° C. The smooth group III nitride semiconductor surface is able be obtained under the condition, but the patterns are unable to be obtained on the group III nitride semiconductor surface.
Therefore, in order to make some specific patterns on the group III nitride semiconductor surface, providing the better semiconductor production technology to the industry, it is necessary to research and develop innovative semiconductor manufacturing process, in order to raise the production efficiency and reduce the manufacturing cost.